This invention relates to a surgical instrument, and in particular to a surgical instrument that can use mechanical energy and/or electrical energy to treat tissue.
Known mechanical surgical instruments include simple scalpels which are used for cutting soft tissue, rotatable shavers which are also used for removing soft tissue, and rotatable burrs which are used for cutting harder tissue such as bone.
Known electrosurgical instruments include monopolar and bipolar devices, both of which are used primarily for treating or cauterising soft tissue. A monopolar electrosurgical device includes a single active electrode and a return electrode, the return electrode being positioned, in use, remotely from the active electrode, usually on the patient""s skin. A bipolar electrosurgical instrument has both active and return electrodes located in close proximity, usually within the one device. Electrical energy passes from the active electrode to the return electrode via tissue being treated, and possibly via an electroconductive fluid surrounding the tip of the instrument. Both monopolar and bipolar electrosurgical instruments are limited by their inability to remove hard tissue such as bone, as they are less efficient and relatively slow in removing such hard tissue.
Typically, therefore, if a surgeon needs to remove hard and soft tissues from the same surgical site, and/or to cauterise and/or to ablate tissue, different surgical instruments would need to be used. For example, an electrosurgical instrument could be used to cut soft tissue, in which case a mechanical instrument (such as a burr) would be needed to cut hard tissue such as bone. The insertion and removal of different surgical instruments through an incision to a surgical site does, however, complicate and lengthen a surgical operation as compared with using a single surgical instrument, as well as adding to the overall costs of instruments needed.
To overcome this disadvantage, it is known to use a surgical instrument which includes a mechanical element, such as a rotary shaver or burr, and an electrosurgical instrument such as a monopolar or bipolar device. A known instrument of this type is described in U.S. Pat. No. 5,904,681, which describes an instrument having a shaver or burr rotatably mounted within an outer sleeve, and a bipolar electrosurgical device mounted at the end of the outer sleeve and adjacent to an apertured end portion thereof through which the rotary shaver or burr acts on hard tissue such as bone. The interior of the sleeve is connected to a source of suction, so that tissue particles removed by the shaver or burr can be removed from the vicinity of the surgical site. The disadvantage of this type of instrument is that tissue debris removed by the electrosurgical device cannot be removed from the vicinity of the surgical site via the sleeve interior by the source of suction provided for removing tissue particles cut by the rotary shaver or burr.
The aim of the invention is to provide a surgical instrument that can cut through both soft and hard tissues using mechanical and electrosurgical devices, and reliably remove tissue particles and debris produced by both the mechanical and electrosurgical means.
The present invention provides a surgical instrument comprising an elongate hollow probe having an apertured region at its distal end portion, an elongate drive shaft disposed within the probe and mounted for rotation about its longitudinal axis within the probe, a cutting tool located at the distal end of the drive shaft and positioned adjacent to the apertured region, an electrosurgical device located at the distal end of the probe adjacent to the apertured region, a motor for rotating the drive shaft, and suction means for providing a source of suction at the apertured region for evacuating tissue debris removed by either the cutting tool or the electrosurgical device
Advantageously, the electrosurgical device is a bipolar electrosurgical device including at least one active electrode, at least one return electrode and an insulator for spacing and insulating the or each return electrode with respect to the or each active electrode.
In a preferred embodiment, the apertured region is constituted by first and second apertures, the cutting tool being positioned to enable tissue to be cut by cutting means provided on the cutting tool, the cutting means being engageable with tissue through the first aperture, and the second aperture being positioned in the region of the electrosurgical device, preferably adjacent thereto.
In a preferred embodiment, the instrument further comprises means for selectively blocking communication between the first aperture and the suction means to allow the suction means to operate principally through the second aperture. In one embodiment, the drive shaft is hollow, the cutting tool is hollow and contiguous therewith, and the distal end portion of the cutting tool is formed with a cut-out through which tissue debris can be evacuated when the cut-out is in alignment with the first aperture. Alternatively, the drive shaft is solid and of a diameter less than that of the hollow probe so as to define a channel between the drive shaft and the hollow probe, tissue debris being removable via the channel.
Advantageously, the blocking means is provided by the cutting tool being configured in such a manner that a portion thereof effectively blocks the first aperture when the cutting tool is in a predetermined rotational position. Preferably, an outer surface of the hollow cutting tool constitutes the means for effectively blocking the first aperture when the cutting tool is in said predetermined position. In one preferred arrangement, the instrument further comprises means for selectively positioning the cutting tool automatically in said predetermined position.
Alternatively, the blocking means comprises a baffle operable to block effectively the first aperture. The baffle may be located on the interior or the exterior of the probe, and is preferably movable between a first position, in which it effectively blocks the first aperture, and a second position in which it is clear of the first aperture. In one arrangement, the baffle is rotatable about the longitudinal axis of the probe between the first and second positions. The baffle may be manually movable between its first and second positions, or alternatively a motor is provided to move the baffle between its first and second positions.
Alternatively, the cutting tool is provided with an abrasive outer surface, the distal end portion of the probe being spaced from the abrasive outer surface to define an inlet through which tissue debris can pass.
Conveniently, there is a single active electrode, and a single return electrode, and the active electrode, the insulator and the return electrode are formed with contiguous apertures in alignment with the second aperture.